Process of making calcium arsenate in dry powdered form



Patented Sept. 9', '1924.

uNrrr-zn STATE-S trachea;

PATENT QFFEQE.

WILLIS K. SIMPSON, OF EAST ORANGE, JERSEY.

PROCESS OF MAKING CALCIUM ARSENATE IN DBY-PGWDEBED FORM,

Ho Drawing.

To all whom it may concern:

a citizen of the United States, and resident of East Orange, in thecounty of Essex and State of New Jersey, have invented certainv new anduseful Improvements inProcesses of Making Calcium Arsenate inDry"Powdered Form, of which the following is a specification. Thisinvention relates to a process of making calcium arscnate, the objectbeing to produce the product in a dry, powdered form, free from solublearsenic salts, suitable for use as an insecticide without furthentreatment, such as grinding, drying,

etc.

The object and distinguishing feature of my process is the rendering ofthe commercial process of manufacture of calcium arflo senate extremelysimple and efiicienhand, consequently, lcssexpensive, avoiding thenecessity of several successive o rations, with the corresponding number0 separate pieces of apparatus and resultant successive 26 handlingportransferring of the part1 treated product from one to the other an also,avoiding the necessity of any further or final treatment of the arsenatetorender it suitable for use as an insecticide, the prod- 30 uctproduced by my process being in the 'dry, powdered form ready for use.

\ To accomplish this result,.I appl a hydrated oxide of arsenic (arsenicacidi to the calcium oxide- (lime) while the latter is being ground. Thegrinding of the calcium oxide may be done in any of the rinding mills,such as the so called ,bal mill,

' which may be provided with a hollow shaft 01 trunnion, or othersuitable arrangement,

40 through which, or by means of \vh1ch, the arsenic acid-is sprayedoverthe lime while the same is being ground in the mills The amount ofarsenic acid used, or the speed of the spraying operation, is regulated4 according to the amount of lime being ground and the' speed ofgrinding, so that there is always an, excess of lime suflieient to takeup or combine with the free water of arsenic Application and June 4,192:. Serial No. 5,352.

the arsenic acid, this action of lime and arsenic acid being well known.

The amount of arsenic acid used is also regulated to produce therequired amount of pent oxide, usually from 30% to int c finishedproduct.

The'degree of fineness of the product so produced is such that it willpass throu h a 100 mesh sieve, or finer, and is'practica y free fromwater soluble arsenic compounds.

This simultaneous "treatment has been found in actual practice to verymaterially aareduce the time and cost of production and to produce avery high grade product, all of which is of great importance inthecommercial production of the insecticide.

What I claim is i 1. The process of making calcium arsenate whichconsists in grinding calcium ox-- ids and applying a hydrated oxide ofar senic thereto simultaneously during the grindingthereof. regulatingthe amount of the hydrated oxide of arsenic so applied to cause theremoval of all of the free water therefrom by the calciumoxide.producing calcium arsenate in a dry powdered form.

2. The process of making calcium arsenate which consists in grindingcalcium oxide and applying arsenic acid simultaneously thereto duringthe rinding thereof, regulating the amount 0 arsenic acid so appliedoxi'de, px oducing calcium arsenate-in a dry 00 powdered form. I

Signed at New York, in the-countyuei New York and State of New York,this 6th day of June, A. D. 1923.

WILLIS i1. SIMPSON.-

